Find X Values Where f(x) Is Negative: Graph Analysis

Inequality Analysis with Graphical Interpretation

Find all values of x x

where f(x)<0 f\left(x\right) < 0 .

XXXYYY-11-11-11-1-1-1-6-6-6

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Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Find all values of x x

where f(x)<0 f\left(x\right) < 0 .

XXXYYY-11-11-11-1-1-1-6-6-6

2

Step-by-step solution

To determine where the function f(x) f(x) is less than 0, observe the graphical representation:

  • The roots are located at x=11 x = -11 , x=6 x = -6 , and x=1 x = -1 . These are the x-values where the function intersects the x-axis.
  • Considering the general behavior of quadratic functions, the function is negative between the outer roots unless it passes through below x-axis at multiple roots due to shape.

The given graph suggests the function dips below the x-axis between x=11 x = -11 and x=1 x = -1 , passing through x=6 x = -6 .

After analyzing the intervals:

  • The interval to the left: x<11 x < -11
  • The interval to the right: x>1 x > -1

Therefore, values of x x for which the function f(x) f(x) is less than 0 are x>1 x > -1 or x<11 x < -11 .

The correct choice is: x>1 x > -1 or x<11 x < -11

3

Final Answer

x>1 x > -1 or x<11 x < -11

Key Points to Remember

Essential concepts to master this topic
  • Graph Reading: Function is negative when curve lies below x-axis
  • Technique: Identify roots at x = -11, -6, -1 and test intervals
  • Check: Verify endpoints are excluded since f(x) < 0, not ≤ 0 ✓

Common Mistakes

Avoid these frequent errors
  • Reading between consecutive roots instead of correct intervals
    Don't assume f(x) < 0 between -11 and -1 just because those are outer roots = wrong interval selection! The graph shows the function is actually positive in that middle region. Always trace the curve carefully to see where it dips below the x-axis.

Practice Quiz

Test your knowledge with interactive questions

The graph of the function below intersects the X-axis at points A and B.

The vertex of the parabola is marked at point C.

Find all values of \( x \) where \( f\left(x\right) > 0 \).

AAABBBCCCX

FAQ

Everything you need to know about this question

How do I know which parts of the graph are negative?

+

Look for sections where the curve is below the x-axis. The graph shows the function dips below zero to the left of x = -11 and to the right of x = -1.

Why isn't the answer just between -11 and -1?

+

That's a common mistake! The graph actually shows the function is positive in the middle section between the roots. You need to look at where the curve actually goes below the x-axis.

What do the roots at -11, -6, and -1 mean?

+

These are x-intercepts where f(x) = 0. They divide the graph into intervals. The root at -6 is where the curve touches the x-axis between the other two roots.

How do I write the final answer correctly?

+

Use or to connect separate intervals: x<11 x < -11 or x>1 x > -1 . Don't use 'and' because x cannot be in both intervals simultaneously!

Should I include the roots in my answer?

+

No! Since we want f(x) < 0 (strictly less than), the roots where f(x) = 0 are not included. Use < or > symbols, not ≤ or ≥.

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